Waste heat recovery device for internal combustion engine

ABSTRACT

A waste heat recovery system for an internal combustion engine. The internal combustion engine includes first and second raised temperature portions. The raised temperature is higher at the first portion than at the second portion. A first evaporating portion generates a first vapor from the first raised temperature portion. A second evaporating portion generates a second vapor from the second raised temperature portion and with a lower pressure than the first vapor. First and second energy converting portions of a displacement type expander converts expansion energy of the first and second vapor into mechanical energy. A condenser and a supply pump are also provided.

This-application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/JP01/00262 which has an Internationalfiling date of Jan. 17, 2001, which designated the United States ofAmerica.

FIELD OF THE INVENTION

The present invention relates to a waste heat recovery system for aninternal combustion engine, particularly to a waste heat recoverysystem, to which Rankine cycle is applied, for recovering waste heat ofthe internal combustion engine that generates at least two, first andsecond raised temperature portions by operation, a degree of raisedtemperature being higher at the first raised temperature portion than atthe second raised temperature portion.

BACKGROUND ART

A known waste heat recovery system of this type is described in JapanesePatent Application Laid-Open No. 6-88523.

However, in the conventional device, raised temperature cooling waterafter cooling an exhaust port of an internal combustion engine isintroduced into a heater provided in an exhaust pipe to generate vapor,and thus has a problem that heat of an exhaust gas having lowertemperature than the raised temperature cooling water is disposed ofwithout being recovered in the heater, thereby reducing a waste heatrecovery rate.

DISCLOSURE OF THE INVENTION

The present invention has an object to provide a waste heat recoverysystem for sufficiently recovering waste heat from at least two raisedtemperature portions generated in an internal combustion engine byoperation, efficiently converting recovered heat energies to mechanicalenergies, and integrating the mechanical energies to be output.

To attain the above described object, the present invention provides awaste heat recovery system for an internal combustion engine, to whichRankine cycle is applied, for recovering waste heat of the internalcombustion engine that generates at least two, first and second raisedtemperature portions by operation, a degree of raised temperature beinghigher at the first raised temperature portion than at the second raisedtemperature portion, wherein the device includes: evaporating meanshaving at least two, first and second evaporating portions, the firstevaporating portion generating a first vapor with raised temperature byusing the first raised temperature portion, while the second evaporatingportion generating a second vapor with raised temperature by using thesecond raised temperature portion and with a lower pressure than thefirst vapor; an expander having at least two, first and second energyconverting portions, the first energy converting portion converting anexpansion energy of the first vapor introduced from the firstevaporating portion into a mechanical energy, while the second energyconverting portion converting an expansion energy of the second vaporintroduced from the second evaporating portion into a mechanical energy,and both mechanical energies being integrated to be output; a condenserfor liquefying the first and second vapors, which are exhausted from theexpander, with dropped pressure after the conversion; and a supply pumpfor supplying liquid from the condenser to the first and secondevaporating portions, respectively.

Configured as described above, waste heat can be sufficiently recoveredfrom each raised temperature portion of the internal combustion engineand integrated to produce relatively high output. The expander in thiscase may be either of displacement type or non-displacement type.

According to the present invention, there is provided a waste heatrecovery system for an internal combustion engine, to which Rankinecycle is applied, for recovering waste heat of the internal combustionengine that generates at least two, first and second raised temperatureportions by operation, a degree of raised temperature being higher atthe first raised temperature portion than at the second raisedtemperature portion, wherein the device includes: evaporating meanshaving at least two, first and second evaporating portions, the firstevaporating portion generating a first vapor with raised temperature bythe first raised temperature portion, while the second evaporatingportion generating a second vapor with raised temperature by using thesecond raised temperature portion and with a lower pressure than thefirst vapor; a displacement type expander having at least two, first andsecond energy converting portions, the first energy converting portionconverting an expansion energy of the first vapor introduced from thefirst evaporating portion into a mechanical energy, while the secondenergy converting portion converting an expansion energy of the secondvapor introduced from the second evaporating portion into a mechanicalenergy, and both mechanical energies being integrated to be output; acondenser for liquefying the first and second vapors, which areexhausted from the displacement type expander, with dropped pressureafter the conversion; and a supply pump for supplying liquid from thecondenser to the first evaporating portion and the second evaporatingportion, respectively.

Configured as described above, the same operation and effect asdescribed above can be obtained. For the displacement type expander, ithas a wide rated operation area, so that even if flow rates of thevapors in the first energy converting portion and the second energyconverting portion vary with variation in temperature at the firstraised temperature portion and the second raised temperature portion inthe internal combustion engine, the expander efficiently operates withina wide rotation area in proportion to the flow rates of the vapors, andintegrates both mechanical energies of the first energy convertingportion and the second energy converting portion to be efficientlyoutput. On the other hand, since the non-displacement type expander hasa narrow rated operation area, it is difficult to efficiently operatewithin a wide rotation area in accordance with variation in flow ratesof the vapors. Thus, to efficiently operate the non-displacement typeexpander, the flow rates of the vapors are to be controlled within arange suited for the rated operation area. In this view, as an expander,the displacement type one may be suitable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a waste heat recovery system, to whichRankine cycle is applied, for an internal combustion engine;

FIG. 2 illustrates a first embodiment;

FIG. 3 is a graph illustrating a relationship between temperature of avapor outlet in evaporating means and thermal efficiency of Rankinecycle;

FIG. 4 illustrates a second embodiment;

FIG. 5 is a vertical sectional view of an expander and corresponds to asectional view taken along a line 5—5 in FIG. 8;

FIG. 6 is an enlarged sectional view around a rotation axis in FIG. 5;

FIG. 7 is a sectional view taken along a line 7—7 in FIG. 5;

FIG. 8 is an enlarged sectional view of essential portions taken along aline 8—8 in FIG. 5;

FIG. 9 illustrates sectional configurations of a rotor chamber and arotor;

FIG. 10 is a front view of a vane body;

FIG. 11 is a side view of the vane body;

FIG. 12 is a sectional view taken along a line 12—12 in FIG. 10;

FIG. 13 is a front view of a seal member; and

FIG. 14 is an enlarged view around a rotation axis in FIG. 7.

BEST MODE FOR CARRYING OUT THE INVENTION

In FIG. 1, a waste heat recovery system 2, to which Rankine cycle isapplied, for an internal combustion engine 1 comprises evaporating means3 for generating a vapor with raised temperature, that is, raisedtemperature vapor, using waste heat of the internal combustion engine 1as a heat source; a displacement type expander 4 for converting anexpansion energy of the raised temperature vapor into a mechanicalenergy to be output; a condenser 5 for liquefying the vapor, which isexhausted from the displacement type expander 4, with droppedtemperature and dropped pressure after the conversion, that is, droppedtemperature/pressure vapor; and a supply pump 6 for pressurizing andsupplying liquid, for example, water, from the condenser 5 to theevaporating means 3.

In FIG. 2, the internal combustion engine 1 generates at least two, inthe embodiment two, first and second raised temperature portions byoperation thereof. A degree of raised temperature is higher at the firstraised temperature portion than at the second raised temperatureportion. In this embodiment, an exhaust port 202 of a cylinder head 201is selected as the first raised temperature portion, and a combustionchamber forming wall 203 of the cylinder head 201 is selected as thesecond raised temperature portion, where a cooling oil passage 204 isplaced. An exhaust manifold may be used as the first raised temperatureportion.

FIG. 3 illustrates a relationship between temperature of a vapor outletin the evaporating means 3 and thermal efficiency of Rankine cycle. Itis apparent in FIG. 3 that higher temperature causes higher thermalefficiency. Thus, the above described two positions are selected as thefirst and second raised temperature portions also in view of easyrecovery of waste heat from the internal combustion engine 1.

The evaporating means 3 has at least two, in the embodiment two, firstand second evaporating portions 205 and 206. The first evaporatingportion 205 has an inlet in the exhaust port 202 and thus generates afirst vapor with raised temperature, that is, a first raised temperaturevapor using an exhaust gas of the exhaust port 202. On the other hand,the second evaporating portion 206 generates a second vapor with raisedtemperature, that is, a second raised temperature vapor by heat exchangeusing raised temperature oil having passed through the cooling oilpassage 204 and with lower temperature and a lower pressure than thefirst raised temperature vapor.

A detailed structure of the displacement type expander 4 will bedescribed later, and the expander 4 has at least two, in the embodimenttwo, first and second energy converting portions 207 and 208. The firstenergy converting portion 207 has a piston and a vane pump structure,and converts an expansion energy of the first raised temperature vaporintroduced from the first evaporating portion 205 into a mechanicalenergy. On the other hand, the second energy converting portion 208shares the vane pump structure, and has functions of converting anexpansion energy of the first vapor, which is introduced from the firstevaporating portion 205, with dropped temperature and dropped pressureafter the conversion, that is, dropped temperature/pressure vapor, intoa mechanical energy, and converting an expansion energy of the secondraised temperature vapor introduced from the second evaporating portion206 into a mechanical energy. In the embodiment, the second raisedtemperature vapor is merged into the dropped temperature/pressure vaporby the first raised temperature vapor, so that the mechanical energiesby the first raised temperature vapor, the dropped temperature/pressurevapor thereof, and the second raised temperature vapor are integrated tobe output from the expander 4 as a rotation energy of an output shaft 23thereof.

The supply pump 6 has a first pump 209 and a second pump 210 forincreasing a pressure that increases a discharge pressure of the firstpump 209. An intake port of the first pump 209 is connected through aconduit 211 to a water tank 212 attached to the condenser 5, and adischarge port thereof is connected through a conduit 213 to an intakeport of the second pump 210. A discharge port of the second pump 210 isconnected through a conduit 214 to a water inlet of a vapor generatingpipe 215 in the first evaporating portion 205, and a discharge pressurethereof is set as a pressure of the first raised temperature vapor, anda vapor outlet thereof is connected through a conduit 216 to a vaporinlet side of the first energy converting portion 207 in the expander 4.

A vapor outlet side of the first energy converting portion 207 isconnected through a vapor passage 217 in the expander 4 to a vapor inletside of the second energy converting portion 208, and a vapor outletside thereof is connected through a conduit 218 to a vapor inlet side ofa cooling passage 219 in the condenser 5. An exhaust side of the coolingpassage 219 is connected through a conduit 220 to the water tank 212.

A discharge port of an oil pump 221 is connected through a lubricatingpassage 222 of the internal combustion engine 1 to an oil inlet of thecooling oil passage 204, and an oil outlet of the cooling oil passage204 is connected through a conduit 223 to an inlet of an oil pipe 224for heat exchange in the second evaporating portion 206. An outlet ofthe oil pipe 224 is connected through a conduit 225 to an intake port ofthe oil pump 211.

A water inlet of a vapor generating pipe 226 in the second evaporatingportion 206 is connected through a conduit 227 to the conduit 213between the first and second pumps 209 and 210, and a vapor outlet ofthe vapor generating pipe 226 is connected through a conduit 228 to thevapor passage 217 between the first and second energy convertingportions 207 and 208 of the expander 4.

In the above described configuration, the internal combustion engine 1is operated and the oil pump 221 is simultaneously driven, and thesupply pump 6 is driven to feed pressure water with a high dischargepressure by the first and second pumps 209 and 210 to the firstevaporating portion 205, and then the first raised temperature vapor isgenerated. In this case, the pressure of the first raised temperaturevapor is set to the discharge pressure of the second pump 210. The firstraised temperature vapor is introduced in the first energy convertingportion 207 in the expander 4, the expansion energy thereof is convertedinto the mechanical energy, and the dropped temperature/pressure vaporafter the conversion is introduced in the second energy convertingportion 208.

On the other hand, pressure water by the first pump 209 with a lowerdischarge pressure than the above described discharge pressure is fed tothe second evaporating portion 206, and then the second raisedtemperature vapor is generated. In this case, a pressure of the secondraised temperature vapor is set to the discharge pressure of the firstpump 209. The second raised temperature vapor is introduced in thesecond energy converting portion 208 in the expander 4, thus the droppedtemperature/pressure vapor and the second raised temperature vapor aremerged, their expansion energies are converted into the mechanicalenergies, and the integrated energy of the mechanical energies by thefirst raised temperature vapor, the dropped temperature/pressure vaporthereof, and the second raised temperature vapor is output as therotation energy of the output shaft 23 in the expander 4.

As described above, the pressure water with the high discharge pressureis fed to the first evaporating portion 205 with a high degree of raisedtemperature, thereby allowing efficient recovery of heat of the exhaustgas in the first evaporating portion 205. On the other hand, pressurewater with the discharge pressure lower than that of the above describedpressure water is fed to the second evaporating portion 206 with a lowerdegree of raised temperature than the first evaporating portion 205,thereby allowing sufficient recovery of heat of raised temperature oilin the second evaporating portion 206 by cooling the combustion chamberforming wall 203. In this case, the pressure water to the secondevaporating portion 206 is taken out from between the first and secondpumps 209 and 210, so that the pressure of the pressure water is set tothe discharge pressure of the first pump 209, thereby allowing reductionin pump loss caused when, for example, a discharge pressure of a highpressure pump is reduced using a throttle.

By the expander 4, the heat energies recovered in the first and secondevaporating portions 205 and 206, thus the expansion energies areefficiently converted into the mechanical energies, and further, theconversion is performed twice from the first raised temperature vapor tofinally integrate the mechanical energies to be output, therebyproducing high output. For example, combined use of the first and secondevaporating portions 205 and 206 allows increase in output by about 12%as compared with the case of using only the first evaporating portion205.

The output taken out of the displacement type expander 4 is proportionalto the flow rate of the vapor of the expander 4, thus an expansion ratioof the first raised temperature vapor is set such that the pressure ofthe dropped temperature/pressure vapor thereof matches the pressure ofthe second raised temperature vapor, thereby increasing a total flowrate of the vapor in the second energy converting portion 208 to allowthe output to be taken out most effectively.

In the embodiment shown in FIG. 4, the cooling oil passage 204 in FIG. 2is replaced by a cooling water passage that functions as a secondevaporating portion 206, a water inlet thereof is connected through aconduit 230 to a conduit 213 between first and second pumps 209 and 210,and a vapor outlet of the second evaporating portion 206 is connectedthrough a conduit 231 to a vapor passage 217 in an expander 4. The otherconfigurations are the same as in FIG. 2, thus like reference numeralsdenote like component parts in FIGS. 2 and 4.

An expander 4 is configured as described below.

In FIGS. 5 to 8, a casing 7 comprises first and second half bodies 8, 9made of metal. Each of the half bodies 8, 9 comprises a main body 11having a substantially oval recess 10 and a circular flange 12 integralwith the main body 11, and the circular flanges 12 are superposed via ametal gasket 13 to form a substantially oval rotor chamber 14. An outersurface of the main body 11 of the first half body 8 is covered with amain body 16, in the form of a deep bowl, of a shell-shaped member 15, acircular flange 17 integral with the main body 16 is superposed on thecircular flange 12 of the first half body 8 via a gasket 18, and threecircular flanges 12, 12, 17 are fastened by a bolt 19 at a plurality ofcircumferential positions. A junction chamber 20 is thereby formedbetween the shell-shaped member 15 and the main bodies 11, 16 of thefirst half body 8.

The main bodies 11 of the half bodies 8, 9 have hollow shaft receivingtubes 21, 22 projecting outwards at their outer surfaces, and by thehollow shaft receiving tubes 21, 22, a large diameter portion 24 of ahollow output shaft 23 penetrating the rotor chamber 14 is turnablysupported via a bearing metal (or a bearing made of resin) 25. An axis Lof the output shaft 23 thereby passes an intersection point of a largediameter and a small diameter in the substantially oval rotor chamber14. A small diameter portion 26 of the output shaft 23 projects outwardsbeyond a hole 27 at the hollow shaft receiving tube 22 of the secondhalf body 9 and is connected to a transmission shaft 28 via splinecoupling 29. The small diameter portion 26 and the hole 27 are sealed bytwo seal rings 30.

Accommodated in the rotor chamber 14 is a circular rotor 31, and a shaftmounting hole 32 at its center is in a fitted relationship to the largediameter portion 24 of the output shaft 23 to provide an engagementportion 33 between the two 31, 24. A rotation axis of the rotor 31thereby matches the axis L of the output shaft 23, thus “L” is commonlyused as reference character of the rotation axis.

The rotor 31 is formed with a plurality of, in this embodiment twelve,slot-shaped spaces 34 radially extending from the shaft mounting hole 32about the rotation axis L at even intervals on the circumference. Eachspace 34 is circumferentially narrow and in substantially U shape in aphantom plane perpendicular to both end surfaces 35 so as tosequentially open into both the end surfaces 35 and an outer peripheralsurface 36 of the rotor 31.

In the respective slot-shaped spaces 34, first to twelfth vane-pistonunits U1 to U12 with the same structure are mounted so as to freelyreciprocate in the respective radial direction as follows. The space 34of substantially U shape is formed with a stepped hole 38 at a portion37 comparting the inner peripheral side of the space 34, and a steppedcylinder member 39 made of ceramic (for example, carbon) is fitted inthe stepped hole 38. An end surface of a small diameter portion a of thecylinder member 39 abuts against an outer peripheral surface of thelarge diameter portion 24 of the output shaft 23, and a small diameterhole b thereof communicates with a through-hole c opening into the outerperipheral surface of the large diameter portion 24. A guide tube 40 isdisposed outside the cylinder member 39 so as to be positioned coaxiallywith the member 39. An outer end of the guide tube 40 is locked by anopening of the space 34 on an outer peripheral surface of the rotor 31,and an inner end of the guide tube 40 is fitted in a large diameter holed of the stepped hole 38 to abut against the cylinder member 39. Theguide tube 40 has a pair of slots e extending from its outer end to itsinner end in an opposed manner, and both the slots e face the space 34.A piston 41 made of ceramic is slidably fitted in a large diametercylinder hole f of the cylinder member 39, and a tip side of the piston41 is always positioned in the guide tube 40.

As shown in FIGS. 5 and 9, a section B of the rotor chamber 14 in aphantom plane A including the rotation axis L of the rotor 31 is formedof a pair of semi-circular sections B1 with their diameters g opposed toeach other and a rectangular section B2 formed by connecting opposed oneend of diameters g of the semi-circular sections B1 to each other andopposed other ends of the diameters g to each other, respectively, andis substantially in the form of an athletic track. In FIG. 9, a partillustrated by a solid line shows the largest section including thelarge diameter, while a part partially illustrated by a double-dottedchain line shows the smallest section including the small diameter. Therotor 31 has a section D slightly smaller than the smallest sectionincluding the small diameter of the rotor chamber 14, as shown by adotted line in FIG. 9.

As is clearly shown in FIGS. 5, 10 to 13, a vane 42 comprises a vanebody 43 in the form of substantially U-shaped plate (horseshoe shape),and a seal member 44 in the form of substantially U-shaped plate mountedto the vane body 43, and a vane spring 58.

The vane body 43 has semi-circular arcuate portions 46 corresponding toan inner peripheral surface 45 by the semi-circular section B1 of therotor chamber 14, and a pair of parallel portions 48 corresponding toopposed inner end surfaces 47 by the rectangular section B2. Eachparallel portion 48 is provided, at its end side, with a rectangularU-shaped notch 49, a rectangular blind hole 50 opening into the bottomsurface, and a short shaft 51 located at a side closer to the end thanthe notch 49 and protruding outwards. Outer peripheral portions of thesemi-circular arcuate portion 46 and both parallel portions 48 aresequentially formed with U-shaped grooves 52 opening outwards, and bothends of the U-shaped grooves 52 respectively communicate with both thenotches 49. Further, both plane parts of the semi-circular arcuateportions 46 are respectively provided with a pair of projecting stripes53 in arched sections. Both the projecting stripes 53 are disposed suchthat an axis L1 of a phantom cylinder thereby matches a straight linewhich bisects a space between the parallel portions 48 andcircumferentially bisects the semi-circular arcuate portion 46. Innerends of the projecting stripes 53 slightly protrude into the spacebetween the parallel portions 48.

The seal member 44 is made of, for example, PTFE and has a semi-circulararcuate portion 55 sliding on the inner peripheral surface 45 by thesemi-circular section B1 of the rotor chamber 14 and a pair of parallelportions 56 sliding on the opposed inner end surfaces 47 by therectangular section B2. Further, a pair of elastic pawls 57 is providedon an inner peripheral surface side of the semi-circular arcuate portion55 so as to be deflected inwards.

The seal member 44 is mounted to the U-shaped groove 52 of the vane body43, a vane spring 58 is fitted in each blind hole 50, and further aroller 59 with a ball bearing structure is mounted to each short shaft51. Each vane 42 is slidably accommodated in each slot-shaped space 34of the rotor 31, where both the projecting stripes 53 of the vane body43 are positioned in the guide tube 40 and opposite side portions of theprojecting stripes 53 are positioned in both the slots e of the guidetube 40, respectively, thereby allowing the inner end surfaces of theprojecting stripes 53 to abut against the outer end surface of thepiston 41. Both rollers 59 are respectively placed in rotatableengagement with a substantially oval annular groove 60 formed on theopposed inner end surfaces 47 of the first and second half bodies 8, 9.A distance between the annular groove 60 and the rotor chamber 14 isconstant throughout their circumferences. Forward motion of the piston41 is converted into rotary motion of the rotor 31 via the vane 42 byengagement between the roller 59 and the annular groove 60.

By the roller 59 cooperating with the annular groove 60, as is clearlyshown in FIG. 8, a semi-circular arcuate tip surface 61 on thesemi-circular arcuate portion 46 of the vane body 43 is always spacedapart from the inner peripheral surface 45 of the rotor chamber 14, andthe parallel portions 48 are always spaced apart from the opposed innerend surface 47 of the rotor chamber 14, thereby reducing frictionlosses. Since a track is regulated by the annular grooves 60 formed oftwo stripes in a pair, the vane 42 is axially rotated at a minutedisplacement angle via the roller 59 by an error between right and lefttracks, and a contact pressure with the inner peripheral surface 45 ofthe rotor chamber 14 is increased. At this time, in the vane body 43 inthe form of substantially U-shaped plate (horseshoe shape), a radiallength of a contact portion with the casing 7 is shorter than that in asquare (rectangular) vane, so that the displacement amount can besubstantially reduced. As is clearly shown in FIG. 5, in the seal member44, the parallel portions 56 are brought into close contact with theopposed inner end surfaces 47 of the rotor chamber 14 by a spring forceof each vane spring 58, and especially exert seal action on the annulargroove 60 via ends of the parallel portions 56 and the vane 42. Thesemi-circular arcuate portion 55 is brought into close contact with theinner peripheral surface 45 by the elastic pawls 57 pushed between thevane body 43 and the inner peripheral surface 45 in the rotor chamber14. That is, the vane 42 in the form of substantially U-shaped plate hasless inflection point than the square (rectangular) vane, which allowsgood close contact. The square vane has corners, which makes it todifficult to maintain the sealing performance. The sealing performancebetween the vane 42 and rotor chamber 14 thereby becomes good. Further,the vane 42 and the rotor chamber 14 are deformed concurrently withthermal expansion. At this time, the vane 42 of substantially U shape isdeformed with evener similar figures than the square vane, therebyreducing variation of clearance between the vane 42 and the rotorchamber 14 and allowing good sealing performance to be maintained.

In FIGS. 5 and 6, the large diameter portion 24 of the output shaft 23has a thick portion 62 supported by the bearing metal 25 of the secondhalf body 9 and a thin portion 63 extending from the thick portion 62and supported by the bearing metal 25 of the first half body 8. In thethin portion 63, a hollow shaft 64 made of ceramic (or metal) is fittedso as to be rotated integrally with the output shaft 23. Inside thehollow shaft 64, a fixed shaft 65 is disposed, which comprises a largediameter solid portion 66 fitted to the hollow shaft 64 so as to befitted in an axial thickness of the rotor 31, a small diameter solidportion 69 fitted to a hole 67 at the thick portion 62 of the outputshaft 23 via two seal rings 68, and a thin hollow portion 70 extendingfrom the large diameter solid portion 66 and fitted in the hollow shaft64. A seal ring 71 is interposed between an end outer peripheral surfaceof the hollow portion 70 and the inner peripheral surface of the hollowshaft receiving tube 21 of the first half body 8.

The main body 16 of the shell-shaped member 15 is mounted, at its innersurface of the central portion, with an end wall 73 of a hollow tube 72coaxial with the output shaft 23 via a seal ring 74. An inner end sideof a short outer tube 75 extending inwards from an outer peripheralportion of the end wall 73 is coupled with the hollow shaft receivingtube 21 of the first half body 8 via a coupling tube 76. On the end wall73, an inner pipe 77 which has a small diameter and is long is providedso as to penetrate the end wall 73, and an inner end side of the innerpipe 77 is fitted to a stepped hole h at the large diameter solidportion 66 of the fixed shaft 65 together with a short hollow connectionpipe 78 projecting therefrom. An outer end portion of the inner pipe 77projects outwards from a hole 79 of the shell-shaped member 15, and aninner end side of a first introduction pipe 80 for raised temperaturevapor inserted from the outer end portion into the inner pipe 77 isfitted in the hollow connection pipe 78. A cap member 81 is screwed onthe outer end portion of the inner pipe 77, and by the cap member 81, aflange 83 of a holder tube 82 for holding the introduction pipe 80 isfixed by pressure to the outer end surface of the inner pipe 77 via aseal ring 84.

As shown in FIGS. 2 and 6, the vapor outlet of the first evaporatingportion 205 is connected through the conduit 216 to the introductionpipe 80. As shown in FIGS. 2 and 5, a through-hole 232 is formed in themain body 16 of the shell-shaped member 15, and the vapor outlet of thesecond evaporating portion 206 is connected through the conduit 228 tothe through-hole 232.

As shown in FIGS. 5 to 7, and 14, a rotary valve V_(R) is provided inthe large diameter solid portion 66 of the fixed shaft 65, and has afunction of supplying and exhausting the vapor to and from each cylindermember 39 with predetermined timing. That is, the first raisedtemperature vapor is supplied to the cylinder member 39 of the first totwelfth vane-piston units U1 to U12 through a plurality of, in thisembodiment twelve, through-holes c successively formed on the hollowshaft 64 and the output shaft 23, and the first droppedtemperature/pressure vapor after expansion is exhausted from thecylinder member 39 through the through-holes c.

A configuration of the rotary valve V_(R) is as follows. As is clearlyshown in FIG. 14, in the large diameter solid portion 66, first andsecond holes 86, 87 extending in opposite directions to each other froma space 85 which communicates with the hollow connection pipe 78 areformed, and the first and second holes 86, 87 open into bottom surfacesof first and second recesses 88, 89 opening into the outer peripheralsurface of the large diameter solid portion 66. First and second sealblocks 92, 93 made of carbon having supply ports 90, 91 are mounted tothe first and second recesses 88, 89, and their outer peripheralsurfaces are rubbed against the inner peripheral surface of the hollowshaft 64. In the first and second holes 86, 87, first and second supplypipes 94, 95 which are coaxial and short are inserted loosely, and taperouter peripheral surfaces i, j of first and second seal tubes 96, 97fitted to tip side outer peripheral surfaces of the first and secondsupply pipes 94, 95 are fitted to inner peripheral surfaces of taperholes k, m inside the supply ports 90, 91 of the first and second sealblocks 92, 93 and connected thereto. The large diameter solid portion 66is formed with first and second annular recesses n, o surrounding thefirst and second supply pipes 94, 95 and first and secondblind-hole-shaped recesses p, q adjacent thereto so as to face the firstand second seal blocks 92, 93, and first and second bellows-shapedelastic bodies 98, 99 are accommodated in the first and second annularrecesses n, o, and, first and second coil springs 100, 101 are fitted inthe first and second blind-hole-shaped recesses p, q, and the first andsecond seal blocks 92, 93 are pressed against the inner peripheralsurface of the hollow shaft 64 by spring forces of the first and secondbellows-shaped elastic bodies 98, 99 and the first and second coilsprings 100, 101.

In the large diameter solid portion 66, formed between the first coilspring 100 and the second bellows-shaped elastic body 99, and betweenthe second coil spring 101 and the first bellows-shaped elastic body 98are first and second recess-shaped exhaust portions 102, 103 alwayscommunicating with two through-holes c, and first and second exhaustholes 104, 105 extending from the exhaust portions 102, 103 in parallelwith the introduction pipe 80 and opening into a hollow portion r of thefixed shaft 65.

The members such as the first seal block 92 and the second seal block 93which are of the same kind and given a word “first” and a word “second”are in a point symmetrical relationship with respect to the axis of thefixed shaft 65.

There is a passage s of the first dropped temperature/pressure vapor inthe hollow portion r of the fixed shaft 65 and in the outer tube 75 ofthe hollow tube 72, and the passage s communicates with the junctionchamber 20 via a plurality of through-holes t penetrating a peripheralwall of the outer tube 75.

As described above, the rotary valve V_(R) is disposed at the center ofthe expander 4, and the first raised temperature vapor supplied throughthe inside of the fixed shaft 65 disposed at the center of the rotaryvalve V_(R) is distributed to each cylinder member 39 concurrently withrotation of the rotor 31, which eliminates the need for intake andexhaust valves used in a general piston mechanism to simplify thestructure. Since the fixed shaft 65 and the hollow shaft 64 mutuallyslide at a small diameter portion with low peripheral velocity, therotary valve V_(R) can have both sealing performance and wearresistance.

As shown in FIGS. 5 and 8, in the outer peripheral portion of the mainbody 11 of the first half body 8, formed around both ends of the smalldiameter of the rotor chamber 14 are first and second introduction holegroups 107, 108 formed of a plurality of introduction holes 106 alignedin the radial direction, and the first dropped temperature/pressurevapor and the second raised temperature vapor in the junction chamber 20are introduced in the rotor chamber 14 via the introduction hole groups107, 108. In the outer peripheral portion of the main body 11 of thesecond half body 9, formed between an end of the large diameter of therotor chamber 14 and the second introduction hole group 108 is a firstleading hole group 110 formed of a plurality of leading holes 109aligned in the radial and peripheral directions, and formed between theother end of the large diameter and the first introduction hole group107 is a second leading hole group 111 formed of a plurality of leadingholes 109 aligned in the radial and peripheral directions. From thefirst and second leading hole groups 110, 111, second droppedtemperature/pressure vapor with further dropped temperature and droppedpressure is exhausted outside by expansion between the adjacent vanes42.

The output shaft 23 or the like is lubricated by water, and thelubricating passage is configured as follows. That is, as shown in FIGS.5 and 6, a water supply pipe 113 is connected to a water supply hole 112formed in the hollow shaft receiving tube 22 of the second half body 9.The water supply hole 112 communicates with a housing 114 which thebearing metal 25 of the second half body 9 side faces, the housing 114communicates with a water passing hole u formed in the thick portion 62of the output shaft 23, the water passing hole u communicates with aplurality of water passing grooves v extending in a generatrix directionof the outer peripheral surface of the hollow shaft 64 (see also FIG.14), and further each water passing groove v communicates with a housing115 which the bearing metal 25 of the second half body 8 side faces. Aninner end surface of the thick portion 62 of the output shaft 23 isprovided with an annular recess w through which the water passing hole ucommunicates with a slide portion between the hollow shaft 64 and thelarge diameter solid portion 66 of the fixed shaft 65.

This causes lubrication between each bearing metal 25 and the outputshaft 23, and between the hollow shaft 64 and fixed shaft 65 by water,and lubrication among the casing 7 and the seal member 44 and eachroller 59 by water having permeated the rotor chamber 14 from the spacebetween the bearing metals 25 and the output shaft 23.

In FIG. 7, the first and seventh vane-piston units U1, U7 in a pointsymmetrical relationship with respect to the rotary axis L of the rotor31 operate in the same way. This applies to the second and eighthvane-piston units U2, U8 in the point symmetrical relationship.

For example, also referring to FIG. 14, an axis of a first supply pipe94 is slightly shifted in a counterclockwise direction with respect to asmall diameter position E of the rotor chamber 14 in FIG. 7, and thefirst vane-piston unit U1 is located in the small diameter position Eand the first raised temperature vapor is not supplied to the largediameter cylinder hole f, and therefore it is assumed that the piston 41and vane 42 are located in a backward position.

From this condition, the rotor 31 is slightly rotated in thecounterclockwise direction in FIG. 7, the supply port 90 of the firstseal block 92 communicates with the through-hole c, and the first raisedtemperature vapor from the first evaporating portion 205 and thus theintroduction pipe 80 is introduced in the large diameter cylinder hole fthrough a small diameter hole b. This causes forward motion of thepiston 41, and since the vane 42 slides toward the large diameterposition F of the rotor chamber 14, the forward motion is converted intorotary motion of the rotor 31. When the through-hole c is shifted fromthe supply port 90, the first raised temperature vapor expands in thelarge diameter cylinder hole f to further move forward the piston 41,thus the rotation of the rotor 31 is continued. The expansion of thefirst raised temperature vapor ends when the first vane-piston unit U1reaches the large diameter position F of the rotor chamber 14.

In this way, the expansion energy of the first raised temperature vaporis converted into the rotary energy of the output shaft 23, which is themechanical energy. Thus, the cylinder member 39, piston 41, vane 42,rotor 31, and casing 7 form the first energy converting portion 207.

Then, by the piston 41 moved backward by the vane 42, the first droppedtemperature/pressure vapor in the large diameter cylinder hole f isexhausted to the junction chamber 20 through a small diameter hole b,through-hole c, first recess-shaped exhaust portion 102, first exhausthole 104, passage s (see FIG. 6), and each through-hole t with therotation of the rotor 31. In the junction chamber 20, the second raisedtemperature vapor introduced in the junction chamber 20 from the secondevaporating portion 206 is merged into the first droppedtemperature/pressure vapor, and the merged vapor is introduced in therotor chamber 14 through the first introduction hole group 107, as shownin FIGS. 5 and 8, and further expands between the adjacent vanes 42 torotate the rotor 31, and then the second dropped temperature/pressurevapor is exhausted outwards from the first leading hole group 110.

In this case, the expansion energy of the merged vapor of the firstdropped temperature/pressure vapor and the second raised temperaturevapor is converted into the rotation energy of the output shaft 23,which is the mechanical energy. Thus, the casing 7, rotor 31, and vane42 form the second energy converting portion 208. Both mechanicalenergies of the first and second energy converting portions 207 and 208are integrated as the rotary energy of the output shaft 23.

The small diameter hole b, through-hole c, first recess-shaped exhaustportion 102 (second recess-shaped exhaust portion 103), first exhausthole 104 (second exhaust hole 105), passage s, each through-hole t,junction chamber 20, and first introduction hole group 107 (secondintroduction hole group 108) form the vapor passage 217 connecting thevapor output side of the first energy converting portion 207 and thevapor inlet side of the second energy converting portion 208.

The displacement type expander 4 may be of the type output only based onthe first and second raised temperature vapors. The expander ispreferably of the displacement type, and as such an expander, notlimited to the piston/vane type, but a vane/vane type or a piston/pistontype displacement type expander may be used. Further, not limited to thedisplacement type expander, but a non-displacement type expander such asof a turbine type may be used.

What is claimed is:
 1. A waste heat recovery system for a heat source,for recovering waste heat of the heat source that generates at leasttwo, first and second raised temperature portions by operation, a degreeof raised temperature being higher at said first raised temperatureportion than at said second raised temperature portion, wherein saidsystem comprises: at least two, first and second evaporating portions,the first evaporating portion generating a first vapor with raisedtemperature by using said first raised temperature portion, while saidsecond evaporating portion generating a second vapor with raisedtemperature by using said second raised temperature portion and with alower pressure than said first vapor; an expander having at least two,first and second energy converting portions, the first energy convertingportion converting an expansion energy of said first vapor introducedfrom said first evaporating portion into a mechanical energy, while saidsecond energy converting portion converting an expansion energy of saidsecond vapor introduced from said second evaporating portion into amechanical energy, and both mechanical energies being integrated to beoutput; wherein said second energy converting portion of said expanderhas a function of converting an expansion energy of the first vapor,which is introduced from said first evaporating portion, with droppedpressure after said conversion, into a mechanical energy.
 2. A wasteheat recovery system for a heat source according to claim 1, wherein anexpansion ratio of said first vapor is set such that a pressure of thedropped pressure vapor matches a pressure of said second vapor.
 3. Awaste heat recovery system for a heat source, for recovering waste heatof the heat source that generates at least two, first and second raisedtemperature portions by operation, a degree of raised temperature beinghigher at said first raised temperature portion than at said secondraised temperature portion, wherein said system comprises: at least two,first and second evaporating portions, the first evaporating portiongenerating a first vapor with raised temperature by using said firstraised temperature portion, while said second evaporating portiongenerating a second vapor with raised temperature by using said secondraised temperature portion and with a lower pressure than said firstvapor; a displacement type expander having at least two, first andsecond energy converting portions, the first energy converting portionconverting an expansion energy of said first vapor introduced from saidfirst evaporating portion into a mechanical energy, while said secondenergy converting portion converting an expansion energy of said secondvapor introduced from said second evaporating portion into a mechanicalenergy, and both mechanical energies being integrated to be output;wherein said second energy converting portion of said displacement typeexpander has a function of converting an expansion energy of the firstvapor, which is introduced from said first evaporating portion, withdropped pressure after said conversion, into a mechanical energy.
 4. Awaste heat recovery system for a heat source according to claim 3,wherein an expansion ratio of said first vapor is set such that apressure of the dropped pressure vapor matches a pressure of said secondvapor.
 5. A waste heat recovery system for an internal combustionengine, to which Rankine cycle is applied, for recovering waste heat ofthe internal combustion engine that generates at least two, first andsecond raised temperature portions by operation, a degree of raisedtemperature being higher at said first raised temperature portion thanat said second raised temperature portion, wherein said systemcomprises: evaporating means having at least two, first and secondevaporating portions, the first evaporating portion generating a firstvapor with raised temperature by using said first raised temperatureportion, while said second evaporating portion generating a second vaporwith raised temperature by using said second raised temperature portionand with a lower pressure than said first vapor; an expander having atleast two, first and second energy converting portions, the first energyconverting portion converting an expansion energy of said first vaporintroduced from said first evaporating portion into a mechanical energy,while said second energy converting portion converting an expansionenergy of said second vapor introduced from said second evaporatingportion into a mechanical energy, and both mechanical energies beingintegrated to be output; a condenser for liquefying said first andsecond vapors, which are exhausted from the expander, with droppedpressure after said conversion; and a supply pump for supplying liquidfrom the condenser to said first and second evaporating portions,respectively; wherein said second energy converting portion of saidexpander has a function of converting an expansion energy of the firstvapor, which is introduced from said first evaporating portion, withdropped pressure after said conversion, into a mechanical energy.
 6. Awaste heat recovery system for an internal combustion engine accordingto claim 5, wherein an expansion ratio of said first vapor is set suchthat a pressure of the dropped pressure vapor matches a pressure of saidsecond vapor.
 7. A waste heat recovery system for an internal combustionengine, to which Rankine cycle is applied, for recovering waste heat ofthe internal combustion engine that generates at least two, first andsecond raised temperature portions by operation, a degree of raisedtemperature being higher at said first raised temperature portion thanat said second raised temperature portion, wherein said systemcomprises: evaporating means having at least two, first and secondevaporating portions, the first evaporating portion generating a firstvapor with raised temperature by using said first raised temperatureportion, while said second evaporating portion generating a second vaporwith raised temperature by using said second raised temperature portionand with a lower pressure than said first vapor; a displacement typeexpander having at least two, first and second energy convertingportions, the first energy converting portion converting an expansionenergy of said first vapor introduced from said first evaporatingportion into a mechanical energy, while said second energy convertingportion converting an expansion energy of said second vapor introducedfrom said second evaporating portion into a mechanical energy, and bothmechanical energies being integrated to be output; a condenser forliquefying said first and second vapors, which are exhausted from thedisplacement type expander, with dropped pressure after said conversion;and a supply pump for supplying liquid from the condenser to said firstand second evaporating portions, respectively; wherein said secondenergy converting portion of said displacement type expander has afunction of converting an expansion energy of the first vapor, which isintroduced from said first evaporating portion, with dropped pressureafter said conversion, into a mechanical energy.
 8. A waste heatrecovery system for an internal combustion engine according to claim 7,wherein an expansion ratio of said first vapor is set such that apressure of the dropped pressure vapor matches a pressure of said secondvapor.